This invention relates to an improved apparatus and method for manufacturing woven products utilizing alternating twist (or net zero twist) yarn. There are a number of methods for producing yarn and fabrics that have a net zero twist.
One method for producing alternating twist yarn is by using reversible motors, which can be used to alternately cause a yarn to be twisted one way and then the other. Such motors, however, are relatively expensive and complex. These motors are also subject to mechanical breakdown. Another means of producing net zero twist yarn is by utilizing a pair of airjets, with the first jet capable of twisting the yarn in the opposite direction to that of the second, and periodically alternating the flow of actuating air from one jet to the other. However, it is found that polymer particles, trimer, loose dyestuff, and other debris can become lodged in the air jet when it is not actuated, preventing subsequent normal operation. This problem is significant since it can destroy the commercial viability of this process.
The use of twisted yarns in woven products is well known in the art. Traditionally, the yarn is passed through a mechanism for applying the twist, and is then rolled back onto a spool or bobbin. The bobbin is then transported to a loom to provide yarn for the weaving process. Thus, using twisted yarns has heretofore been a two-step process.
Thus, it would be desirable to provide an apparatus and method for alternately twisting yarn that allows the yarn to be twisted and woven in a single continuous, streaming step. Another desirable feature would be to provide an in-line air-jet yarn twisting apparatus that significantly reduces or eliminates the problem of debris becoming lodged in the air jet when it is not actuated. One effort to solve a few of these problems is described in U.S. patent application Ser. No. 08/725,647, filed Oct. 1, 1996, which is hereby incorporated herein by specific reference in its entirety.